Cloud based file system surpassing device storage limits

ABSTRACT

Technology is disclosed herein for a cloud based file system that can surpass physical storage limit. According to at least one embodiment, a computing device includes a file system having multiple storage objects. The metadata of the storage objects are stored in local storage of the computing device. A remote storage server is responsible for storing the content data of the storage objects. The computing device presents the storage objects via an output device as if the content data are stored locally in the computing device. The computing device identifies some of the storage objects that have a high possibility to be read by computer applications of the computing device, and caches the content data of these storage objects locally.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Application No. PCT/US2013/063003, entitled “CLOUD BASED FILED SYSTEM SURPASSING DEVICE STORAGE LIMITS”, which was filed on Oct. 2, 2013, which claims to the benefit of U.S. Provisional Patent Application No. 61/708,794, entitled “CLOUD COMPUTING INTEGRATED OPERATING SYSTEM”, which was filed on Oct. 2, 2012, both of which are incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

At least one embodiment of the present invention pertains to cloud storage service, and more particularly, to computing device having a cloud based file system that can surpass device storage limits.

BACKGROUND

Cloud storage service is popular nowadays for providing online storage space to host user files. Users of a cloud storage service can upload files to the cloud and later access the uploaded files over the internet from the same or a different computing device.

A cloud storage service can provide client applications for different types of computing devices. A user can use a computing device to download and install a client application of the cloud storage service at the device. The client application can enable the user to drop any file into a designated folder. Any file in the designated folder is synchronized with the cloud storage service. The user can then use the device or other devices having a client application installed to access these synchronized files stored at the cloud storage service. The cloud storage service can further provide a web interface. Through the web interface, a user can upload files to and download files from the cloud storage service, without the need of installing the client application.

The user needs to manually decide which files to be synchronized by dropping the files into the designated folder or drive. The designated folders or drives are generally treated as external folders or drives by the operating systems of the computing devices. The operating systems do not rely on the designated folders or drives to perform, and do not utilize the designated folders or drives to perform any operating system related tasks.

SUMMARY

Technology introduced herein provides a mechanism to enable a cloud based file system that can surpass physical storage limit. According to at least one embodiment, a computing device includes a file system having multiple storage objects (e.g., files). The metadata of the storage objects are stored in local storage of the computing device. A remote storage server is responsible for storing the content data of the storage objects. The computing device presents the storage objects via an output device as if the content data are stored locally in the computing device. The computing device can further identify some of the storage objects that have a high possibility to be read by computer applications of the computing device, and caches the content data of these storage objects locally.

Because the remote storage server is responsible for storing the content data of the storage objects, the local storage of the computing device only needs to store the metadata of the storage objects to maintain and manage the storage objects of the file system. Since the storage space required for storing the metadata is much less than the storage space required for storing the content data of the storage objects, the computing device is capable of having a file system including files having a total size larger than the physical storage limit of the local storage of the computing device. Due to the scalability of the remote storage server, technically the computing device can have a file system with an infinite size limitation.

In accordance with the techniques introduced here, therefore, a method for managing a device file system integrated with a storage server is provided. The method stores metadata of a plurality of storage objects included by a file system of the computing device at the computing device. Storage server stores content data of the plurality of storage objects. The method can present one or more of the plurality of storage objects to a user of the computing device as if the content data of the storage objects are stored locally in the computing device. The method determines, at the computing device, at least one storage object of the plurality of storage objects, the object having a high possibility to be read by computer applications of the computing device. The method then caches, at the computing device, the content data of the at least one storage object.

In accordance with the techniques introduced here, therefore, a computing device having a file system that can surpass physical storage limit is also provided. The computing device includes a processor, a file system manager, a storage component, and a networking component. The processor is configured to identify one of multiple files of the computing device that has a high probability to be read by the computing device. The file system manager, when executed by the processor, controls the files and handles file system operations to the files. The storage component is configured to store metadata of the files without permanently storing content data of the files, wherein a storage server stores the content data of the files. The networking component is configured to retrieve and cache the content data of the file from the storage server after the processor identifies the file as having the high probability. The file system manager is capable of controlling files having a total size exceeding a physical storage limit of the storage component.

In accordance with the techniques introduced here, therefore, a method is also provided. The method receives, at a file system manager of a computing device, an instruction to create a file stored at the computing device from a first application running at the computing device. Accordingly the method creates, by the file system manager, the file by storing metadata of the file in a local storage device of the computing device and transmitting content data of the file to a storage server. The computing device can also continue to keep the content data of the file locally. The metadata includes a link to a location where the storage server stores the content data of the file. The method further receives, at the file system manager, an instruction to read the file from a second application running at the computing device. The method then retrieves, by the file system manager, the content data of the file from the storage server based on the metadata including the link to the location. The method provides, by the file system manager, the content data to the application as if the local storage device stores the content data of the file.

Other aspects of the technology introduced here will be apparent from the accompanying figures and from the detailed description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and characteristics of the present invention will become more apparent to those skilled in the art from a study of the following detailed description in conjunction with the appended claims and drawings, all of which form a part of this specification. In the drawings:

FIG. 1 illustrates an example system for computing devices connected to a cloud storage server.

FIG. 2 contains a diagram illustrating an example operating system of a computing device.

FIG. 3 illustrates an example of photo devices connected to a cloud-based server.

FIG. 4 illustrates an example of a process for managing a device file system integrated with a storage server.

FIG. 5 illustrates an example of an alternative process for a cloud based file system that can surpass device storage limit.

FIG. 6A contains a block diagram illustrating example components of a local prefetching module for an electronic device.

FIG. 6B contains a diagram illustrating an example usage profile maintained by a local profile manager.

FIG. 6C contains a diagram illustrating an example prefetching profile received by a local profile manager.

FIG. 6D contains a block diagram illustrating example components of the global prefetching module.

FIG. 7 contains a flowchart illustrating an example operation of a global profile manager.

FIG. 8 contains a flowchart illustrating an example operation of the local prefetching module.

FIG. 9 contains a high-level block diagram showing an example architecture of a computer server, which may represent any computer described herein.

DETAILED DESCRIPTION

References in this specification to “an embodiment,” “one embodiment,” or the like, mean that the particular feature, structure, or characteristic being described is included in at least one embodiment of the present invention. Occurrences of such phrases in this specification do not all necessarily refer to the same embodiment, however.

FIG. 1 illustrates an example system for computing devices connected to a cloud storage server. The system includes a cloud server 110 configured to communicate with the computing devices. In one embodiment, the cloud server 110 can be a server cluster having computer nodes interconnected with each other by a network. The cloud server 110 can contain storage nodes 112. Each of the storage nodes 112 contains one or more processors 114 and storage devices 116. The storage devices can include optical disk storage, RAM, ROM, EEPROM, flash memory, phase change memory, magnetic cassettes, magnetic tapes, magnetic disk storage or any other computer storage medium which can be used to store the desired information.

The computing devices 130 and 140 can each communicate with the cloud server 110 via network 120. The network 120 can be, e.g., the Internet. Although FIG. 1 illustrates two computing devices 130 and 140, a person having ordinary skill in the art will readily understand that the technology disclosed herein can be applied to a single computing device or more than two computing devices connected to the cloud server 110.

The computing device 130 includes an operating system 132 to manage the hardware resources of the computing device 130 and provides services for running computer applications 134 (e.g., mobile applications running on mobile devices). The computer applications 134 stored in the computing device 130 require the operating system 132 to properly run on the device 130. The computing device 130 includes at least one local storage device 138 to store the computer applications and user data. The computing device 130 or 140 can be a desktop computer, a laptop computer, a tablet computer, an automobile computer, a game console, a smart phone, a personal digital assistant, or other computing devices capable of running computer applications, as contemplated by a person having ordinary skill in the art.

The computer applications 134 stored in the computing device 130 can include applications for general productivity and information retrieval, including email, calendar, contacts, and stock market and weather information. The computer applications 134 can also include applications in other categories, such as mobile games, factory automation, GPS and location-based services, banking, order-tracking, ticket purchases or any other categories as contemplated by a person having ordinary skill in the art.

The operating system 132 of the computing device 130 can include a file system manager 136 to manage the file system of the computing device 130. Instead of storing all content data of the files of the file system directly in the local storage device 138 of the computing device 130, the file system manager 136 can identify certain portions of the files suitable to be stored at the cloud server 110. The file system manager can store metadata of the files in the local storage device 138 and sends out content data of the files to the cloud server 110 so that the cloud server 110 stores the content data.

The computer applications 134 running at the computing device 130 need not be aware that the content data of the files are stored in the cloud server 110, instead of the local storage device 138. The computer applications 134 can read data from or write data to the files as if the files are stored in the local storage device 138. For instance, the computer applications 134 can generate read or write request having a location link of the file, in order to read or write data from a specific location of the file. The file system manager 136 is responsible to retrieve the content data of the file from the cloud server 110 to satisfy the read or write requests. The file system manager 136 can further cache certain content data of one or more files, when the file system manager 136 determines that these files has a high probability to be read or written by the applications 134 of the computing device 130.

In order to manage the files with content data stored in a remote cloud storage server, the operating system of the computing device can include a file manager module and a local prefetching module. FIG. 2 illustrates an example operating system 200 including a file manager module 220 and a local prefetching module 230. In one embodiment, the operating system 200 includes a kernel 204. The kernel 204 controls the computer applications running on top of the kernel 204. It provides interfaces to the hardware of the electronic device, thereby isolating the computer applications from the hardware. It may also include one or more intervening sources that can affect the execution of a computer application. For example, the kernel 204 may include a network I/O module 206, a file I/O module 208, a multi-threading module 210, a user input module 214, a system interrupts module 216, and a shared memory access module 218.

In one embodiment, the file system manager 220 is responsible for managing a file system including files with content data stored in a remote cloud storage server. The file system manager 220 can run on top of the kernel 204 as illustrated in the FIG. 2, or run as a part of the customized kernel 204. The local prefetching module 230 can also run on top of the kernel 204, or run as a part of the customized kernel 204. As one example, the local prefetching module 230 can run in a user space file system (e.g. FUSE) on top of a Linux or Android kernel. The local prefetching module 230 can be a module of the operating system 200 separate from the file system manager 220, or alternatively performs as a part of the file system manager 220.

The file system manager 220 maintains a file system including multiple files. The metadata of the files are stored in the local storage, while the content data of the files are stored in a remote cloud storage server. The file system manager 220 presents the files to the applications and users of the computing device, as if the content data are stored locally. The local prefetching module 230 is responsible to retrieve content data from the storage server as cache data based on the access pattern and other factors.

The technology disclosed herein can be applied to various computing devices including, e.g., photo devices. For instance, FIG. 3 illustrates an example of photo devices connected to a cloud-based server. As depicted in FIG. 3, a server 300 may provide a cloud-based service for storing content data of the photo files of the photo devices 311-313. The server 300 can further storing content data of other files of the photo devices, e.g., user profile files, application program files or operating system files. The network 320 can be, e.g., the Internet. Examples of photo devices 311, 312 and 313 may include, but are not limited to, a mobile phone, a smartphone, a personal digital assistant (PDA), a tablet, a mobile game console, a laptop computer, a desktop computer, or any other devices having communication capability.

The photo device 311-313 stores the metadata, e.g., the exchangeable image file format (EXIF) information and thumbnails of the photo files locally. The server 300 stores the content data of the photo files.

In some embodiments, server 300 may also monitor the file access patterns of the photo devices 311-313 and send content data of the files as cache data. For example, in some embodiments, server 300 may determine or identify, a photo file of photo device 311 that is frequently accessed and likely will be read again in near future. The server 300 may notify the device 311 and send the content data of the photo device 311. The photo device 311 caches the content data of that photo file so that a read request of the photo file can be satisfied locally without sending a request to the server 300.

A person having ordinary skill in the art can readily understands that the types of device illustrated in FIG. 3 can be different. For example, photo devices 311, 312 and 313 can be, e.g., tablets, smart phones or laptop computers respectively. The server 300 is capable of storing content data of files designed for these different types of devices.

In order to achieve a file system exceeding the storage limit of local storage, the file system of the computing device is integrated with a storage server so that content data of the files can be stored in the storage server. The storage server acts as a remote high-performance scalable surrogate hardware resource for storing the content data of the files. FIG. 4 illustrates an example of a process 400 for managing a device file system integrated with a storage server. The process 400 starts at step 405, where the computing device stores metadata of a plurality of storage objects (e.g. files) in a file system of the computing device, wherein a storage server stores content data of the plurality of storage objects. The computing device may store some of the content data as cache data. At least one of the content data of the plurality of storage objects is not stored locally in the computing device such that a maximum size of the file system can exceed a physical storage limit of the computing device.

The metadata of a storage object can include, e.g., means of creation of data in the storage object, purpose of data in the storage object, time and date of creation of the storage object, creator or author of data of the storage object, location on the storage server where the content data of the storage object are stored, title of the content data of the storage object, an inode data structure of the storage object, version information, or a sample presentation of the content data of the storage object. The sample presentation of the content data of the file can include, e.g., a reduced-size version of the content data, a sample clip or image of the content data, first few bytes of a set of streaming data, or a reduced-data-rate version of the content data.

At step 410, the computing device presents one or more of the plurality of storage objects to a user of the computing device as if the content data of the storage objects are stored locally in the computing device. For instance, the computing device can use an output component to visualize a preview of at least one file of the files using the metadata of the file as if the content data of the file are stored locally in the storage component.

At step 415, the computing device determines at least one storage object of the plurality of storage objects that has a high possibility to be read by computer applications of the computing device. For instance, the at least one storage object that has the high possibility to be read by the computer applications can be determined based on an access pattern to the plurality of storage objects on the computing device. At step 420, the computing device caches the content data of the at least one storage object.

The cached content data can be used for satisfying future read requests. For instance, at step 425, the computing device receives a read request for a storage object from one of the computer applications running at the computing device. At step 430, the computing device determines whether the content data of the storage object is cached at the computing device. If the content data of the storage object is cached at the computing device, at step 435, the computing device reads the content data of the storage object from its cached location at the computing device. If the content data of the storage object is not cached at the computing device, at step 440, the computing device requests the content data of the storage object from the storage server.

At step 445, the computing device receives a write request for a storage object from one of the computer applications. At step 450, the computing device determines whether the content data of the storage object is cached at the computing device. If the content data of the storage object is cached at the computing device, at step 455, the computing device updates the storage object based on the write request. At step 460, the computing device synchronizes the updated storage object with the content data of the storage object in the storage server. If the content data of the storage object is not cached at the computing device, at step 465, the computing device records a sequential list of changes to the storage object based on the write request into a log data structure. At step 470, the computing device sends the log data structure to the server so that the server applies the sequential list of changes to one or more storage objects stored in the server based on the log data structure.

Those skilled in the art will appreciate that the logic illustrated in FIG. 4 and described above, and in each of the flow diagrams discussed below if any, may be altered in a variety of ways. For example, the order of the logic may be rearranged, substeps may be performed in parallel, illustrated logic may be omitted, other logic may be included, etc. For instance, the write request may be received and handled by the computing device before receiving and handling the read request. Alternatively, the write and read requests can be received and handled in separate processes.

A file system manager of a computing device can be responsible for creating the files in a way that metadata are stored in the local storage and that content data of the files are stored remotely. FIG. 5 illustrates an example of an alternative process 500 for a cloud based file system that can surpass device storage limit. The process 500 starts at step 505, where a file system manager of a computing device receives an instruction from a first application running at the computing device to create a file stored at the computing device. The file system manager maintains a file system including files for the computing device having a total size larger than a storage limit of the local storage device of the computing device.

At step 510, the file system manager creates the file by storing metadata of the file in a local storage device of the computing device and transmitting content data of the file to a storage server, wherein he metadata include a link to a location where the storage server stores the content data of the file. Applications running at the computing device can read files managed by the file system manager of the computing device as if the content data of the files are stored in the local storage device of the computing device. In some embodiments, the storage server stores at least a portion of the metadata of the file as well. For instance, the storage server may store file information data structures (e.g. inodes) for the content data, so that the storage server can identify the files to which the content data belong.

At step 515, the computing device presents, via an output device (e.g. display) of the computing device, the file as a file stored in the local storage device of the computing device based on the metadata of the file. The computing device may display or present, e.g., the filename, the directory in which the file is located, and a preview content (e.g., a thumbnail image or a preview clip) of the file. The user of the computing device perceives that the content of the file is locally stored in the computing device.

At step 520, the file system manager identifies a file having a tendency to be read by the computing device in future based on a file access pattern discovered by the file system manager. The file system manager can identify such tendency in different ways, e.g., as illustrated in diagrams discussed below. At step 525, the file system manager caches the identified file in the local storage device by retrieving the content data of the identified file from the storage server.

At step 530, the file system manager receives an instruction to read the file from a second application running at the computing device. The first application which instructs to create the file and the second application which instructs to read the file may be the same application or different applications. For example, the first and second applications can be the same word processing application that instructs to create and later to read a document file. Alternatively in another example, the first application can be a file explorer application controlled by a user to create a new document file, while the second application can be a separate word processing application to read the document file.

At step 535, the file system manager determines whether the content data of the file is cached locally in the computing device. If so, at step 540, the file system manager provides the location of the locally cached content data to the second application. Otherwise, at step 545, the file system manager retrieves the content data of the file from the storage server based on the metadata including the link to the location. For instance, the file system manager may examine the metadata of the file to identify the location on the storage server where the content data of the file is stored, and then request the content data with the location from the storage server. At step 550, the file system manager provides the content data to the application as if the local storage device stores the content data of the file.

The file system manager may use a local prefetching module to determine the content data of the files to be cached. FIG. 6A contains a block diagram illustrating example components of a local prefetching module 630 for an electronic device. In one embodiment, the local prefetching module 630 includes a local data manager 632, a local profile manager 634 and a request handler 636.

In one embodiment, the local profile manager 634 maintains one or more usage profiles in the primary store and sends them to the prefetching server. It can send the usage profiles periodically, as soon as there is an update, in response to a request from the prefetching server, and so on. FIG. 6B contains a diagram illustrating an example usage profile. A usage profile can contain any information about the activities performed on the electronic device in terms of required files. In one embodiment, the usage profile contains any information on access to the files stored in the primary store. Such information can include the name of a file, the type of the file (partial computer application, full computer application, application data, etc.), the size of the file, the time of access to the file, the type of access (read, write, etc.), the location of the electronic device at the time of access, and so on.

In one embodiment, the local profile manager 634 also receives prefetching profiles from the prefetching server and stores them in the primary store. It can also send requests to the prefetching server for the prefetching profiles periodically, when it has extra bandwidth available, and so on. FIG. 6C contains a diagram illustrating an example prefetching profile. A prefetching profile specifies files to be preloaded on an electronic device in anticipation of the user performing activities which require the files. For each of the specified files, information regarding the name, the type, the size, the access type, the likelihood that it is to be accessed within a predetermined timeframe, etc. can be included.

In one embodiment, the local data manager 632 sends requests to the cloud service to retrieve specific computer applications or application data. It can also send requests to whichever separate servers are hosting the computer applications or application data. In addition, the local data manager 632 receives the requested computer applications or application data and stores them in the primary store or the secondary store on the electronic device. The pace of sending the requests and storing the requested computer applications or application data can depend on where the requested computer applications or application data are to be stored, When they are to be stored in the primary store on the electronic device, it generally means that they are to be accessed immediately and the sending and storing could be performed without much delay, while when they are to be stored in the secondary store, it generally means that they are likely to be accessed in the near future and the sending and storing can be performed with some flexibility in timing.

In one embodiment, given a prefetching profile, the local data manager 302 determines which requests for file retrieval to send and in what order. It may first filter the prefetching profile to remove any file that is already present in the primary store. Next, in one example, it may decide that requests are to be sent for all the files specified in the prefetching profile as the number of such files is small. In another example, it may decide that requests would first be sent for a predetermined number of files with the highest likelihoods or with the shortest time frames. On the other hand, when the size of the secondary store is limited, the local data manager 632 can enforce overwrite policies, such as cache algorithms known to someone of ordinary skill in the art.

In one embodiment, the request handler 636 accepts user requests for certain files and ultimately serves those files from the primary store. In general, it may first look in the primary store, which has pre installed or previously installed files. If the requested file is not there, it looks in the secondary store, which has prefetched files. It saves the requested file in the primary store before serving it in response to user requests.

The prefetching server hosts a global prefetching module. FIG. 6D contains a block diagram illustrating example components of the global prefetching module 660. In one embodiment, the global prefetching module 660 includes a global data manager 662, a global profile manager 664 and an analysis engine 666.

In one embodiment, the global data manager 662 receives requests for computer applications or application data from the electronic devices and forwards them to the cloud service or other sources. The global data manager 662 also receives the requested computer applications or application data from the cloud service or other sources and forwards them to the electronic devices. The pace of forwarding the requests and the requested computer applications or application data can similarly depend on where the requested computer applications or application data are to be stored, as discussed above.

In one embodiment, the global profile manager 664 receives usage profiles from the electronic devices and forwards them to the cloud service for storage. It can forward a usage profile to the cloud service immediately upon receiving it from an electronic device. It can also forward the usage profiles received from an electronic device according to a preset schedule. In addition, it can forward the usage profiles received from multiple electronic devices in batches of a predetermined size or periodically. The global profile manager also maintains a global index of usage profiles in the local storage device indicating how to access the usage profiles stored with the cloud service.

In one embodiment, the global profile manager 664 also receives prefetching profiles from the cloud service and forwards them to the electronic devices. Similarly, it can forward a prefetching profile to the appropriate electronic device immediately or in response to a request from the electronic device for a prefetching profile. It can also wait to forward the prefetching profile together with a response to the next request from the electronic device, such as a request to retrieve certain computer application or application data. In addition, it can forward the prefetching profiles to one or more electronic devices according to a predetermined schedule.

In one embodiment, the analysis engine 666 manages analytical algorithms, the input to which are usage profiles and the output from which are prefetching profiles. Many types of analysis can be performed on the usage profiles, individually and collectively, to detect usage patterns. According to various embodiments, the usage profiles may indicate that on an electronic device, a computer application or a part thereof is often executed or a piece of application data is often used on a certain day or at a certain time, when the computer application or the piece of application data has a certain size, immediately before or after another computer application or piece of application data, when the electronic device is at a certain location, when another electronic device is connected to the prefetching server, etc. The lack of execution or use can also be incorporated into the usage patterns.

Some example usage patterns are described as follows. Different levels of a game may often be accessed in an increasing order. The last few very difficult levels may never be accessed, and the levels before the currently accessed levels may also never be accessed again. The photos or soundtracks in an album may often be accessed in the listed order. More recent albums may be accessed more frequently. Larger files may often be accessed on devices with better resources. Business-related files may often be accessed during the day or on an electronic device in the office, while files pertaining to entertainment may often be accessed at night or on an electronic device at home. Best-selling books in a city may be frequently accessed in that city and surrounding cities. Therefore, different files can be associated with different access patterns, which can be learned from the usage profiles without knowing the nature of the files.

In one embodiment, each analytical algorithm takes into consideration one or more of the usage patterns and selects a set of files for an electronic device that are likely to be accessed in the near future on the electronic device. It can assign different weights to different usage patterns. For example, it can prefer usage patterns reflecting more recent activities across electronic devices. It can also give more weight to usage patterns specific to the electronic device and/or those electronic devices owned by users similar to the owner of the electronic device. Furthermore, it can apply any classification, pattern-recognition and other techniques known to someone of ordinary skill in the art.

In one embodiment, the analysis engine 666 chooses one of the analytic algorithms, based on predetermined rules, user input, etc., and submits a request to the cloud service for executing the chosen analytic algorithm. In response, the cloud service executes the chosen analytic algorithm on the stored usage profiles in a distributed manner and generates resulting prefetching profiles for the electronic devices. The analysis engine 666 can submit a request as soon as a predetermined number of updated usage profiles are stored with the cloud service, according to a preset schedule, when the rate of file retrieval is high indicating a low degree of prefetching success, and so on.

FIG. 7 contains a flowchart illustrating an example operation of a global profile manager. In one embodiment, the global profile manager receives usage profiles from the electronic devices at step 702. It forwards the usage profiles to the cloud service for storage at step 704. Subsequently, the global profile manager submits a request to execute an analytical algorithm maintained by the analysis engine to the cloud service at step 706. When the execution is complete, the global profile manager receives prefetching profiles for the electronic devices at step 708. Finally, it forwards each of the prefetching profiles to the appropriate electronic device at step 710.

FIG. 8 contains a flowchart illustrating an example operation of a local prefetching module. In one embodiment, the request handler accepts a user request and determines whether a requested file is present in the primary store at step 802. If the file is present, it serves the file at step 804. If the file is not present, it determines whether the file is present in the secondary store at step 806. If the file is present, it moves the file to the primary store at step 808 and serves the file at step 810. If the file is not present, the local data manager retrieves the file from a source at step 812 and stores the retrieved file in the primary store at step 814.

FIG. 9 contains a high-level block diagram showing an example architecture of a computer, which may represent any device, any server, or any node within a cloud service as described herein. The computer 900 includes one or more processors 910 and memory 920 coupled to an interconnect 930. The interconnect 930 shown in FIG. 9 is an abstraction that represents any one or more separate physical buses, point to point connections, or both connected by appropriate bridges, adapters, or controllers. The interconnect 930, therefore, may include, for example, a system bus, a Peripheral Component Interconnect (PCI) bus or PCI-Express bus, a HyperTransport or industry standard architecture (ISA) bus, a small computer system interface (SCSI) bus, a universal serial bus (USB), IIC (I2C) bus, or an Institute of Electrical and Electronics Engineers (IEEE) standard 1394 bus, also called “Firewire”.

The processor(s) 910 is/are the central processing unit (CPU) of the computer 900 and, thus, control the overall operation of the computer 900. In certain embodiments, the processor(s) 910 accomplish this by executing software or firmware stored in memory 920. The processor(s) 910 may be, or may include, one or more programmable general-purpose or special-purpose microprocessors, digital signal processors (DSPs), programmable controllers, application specific integrated circuits (ASICs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), trusted platform modules (TPMs), or the like, or a combination of such devices.

The memory 920 is or includes the main memory of the computer 900. The memory 920 represents any form of random access memory (RAM), read-only memory (ROM), flash memory, or the like, or a combination of such devices. In use, the memory 920 may contain code 970 containing instructions according to the techniques disclosed herein.

Also connected to the processor(s) 910 through the interconnect 930 are a network adapter 940 and a storage adapter 950. The network adapter 940 provides the computer 900 with the ability to communicate with remote devices, over a network and may be, for example, an Ethernet adapter or Fibre Channel adapter. The network adapter 940 may also provide the computer 900 with the ability to communicate with other computers. The storage adapter 950 allows the computer 900 to access a persistent storage, and may be, for example, a Fibre Channel adapter or SCSI adapter.

The code 970 stored in memory 920 may be implemented as software and/or firmware to program the processor(s) 910 to carry out actions described above. In certain embodiments, such software or firmware may be initially provided to the computer 900 by downloading it from a remote system through the computer 900 (e.g., via network adapter 940).

The techniques introduced herein can be implemented by, for example, programmable circuitry (e.g., one or more microprocessors) programmed with software and/or firmware, or entirely in special-purpose hardwired circuitry, or in a combination of such forms. Software or firmware for use in implementing the techniques introduced here may be stored on a machine-readable storage medium and may be executed by one or more general-purpose or special-purpose programmable microprocessors.

A “machine-readable storage medium”, as the term is used herein, includes any mechanism that can store information in a form accessible by a machine (a machine may be, for example, a computer, network device, cellular phone, personal digital assistant (PDA), manufacturing tool, any device with one or more processors, etc.). For example, a machine-accessible storage medium includes recordable/non-recordable media (e.g., read-only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; etc.), etc.

In addition to the above mentioned examples, various other modifications and alterations of the invention may be made without departing from the invention. Accordingly, the above disclosure is not to be considered as limiting and the appended claims are to be interpreted as encompassing the true spirit and the entire scope of the invention. 

What is claimed is:
 1. A method for managing a device file system integrated with a storage server, comprising: storing, at a computing device, metadata of a plurality of storage objects in a file system of the computing device without permanently storing content data of the plurality of storage objects, wherein a storage server stores the content data of the plurality of storage objects, wherein a file system manager controls the plurality of storage objects and handles file system operations to the plurality of storage objects, wherein the file system manager is capable of controlling storage objects having a total size exceeding a physical storage limit of the computing device; visualizing a preview of one or more of the plurality of storage objects using the metadata of the one or more storage objects as if the content data of the one or more storage objects are stored locally at the computing device, wherein the metadata includes a sample presentation of the content data of the one or more storage objects, the sample presentation including at least one of: one or more bytes of a set of streaming data corresponding to a portion of the content data, or a reduced-data-rate version of the content data; identifying, at the computing device, at least one storage object of the plurality of storage objects that has a high possibility to be read by the computing device; retrieving content data of the at least one storage object from the storage server after the at least one storage object is identified; and storing, at the computing device, the content data of the at least one storage object for a time period.
 2. The method of claim 1, wherein at least one of the content data of the plurality of storage objects is not stored locally in the computing device such that a maximum size of the file system exceeds the physical storage limit of the computing device.
 3. The method of claim 1, wherein the metadata of a storage object include means of creation of data in the storage object, purpose of data in the storage object, time and date of creation of the storage object, creator or author of data of the storage object, location on the storage server where the content data of the storage object are stored, title of the content data of the storage object, an inode data structure of the storage object, version information or a sample presentation of the content data of the storage object.
 4. A computing device having a file system that can surpass physical storage limit, comprising: a processor configured to identify one of multiple files of the computing device that has a high probability to be read by the computing device; a file system manager which, when executed by the processor, controls the files and handles file system operations to the files; a storage component configured to store metadata of the files without permanently storing content data of the files, wherein a storage server stores the content data of the files; a networking component configured to retrieve the content data of the file from the storage server after the processor identifies the file; wherein the storage component is further configured to store the retrieved content data of the file for a time period; wherein the file system manager is capable of controlling files having a total size exceeding a physical storage limit of the storage component; and an output component configured to visualize a preview of at least one file of the files using the metadata of the file as if the content data of the file are stored locally in the storage component, wherein the metadata includes a sample presentation of the content data of the file, the sample presentation including at least one of: one or more bytes of a set of streaming data corresponding to a portion of the content data, or a reduced-data-rate version of the content data.
 5. The computing device of claim 4, further comprising: an output component configured to present one or more of the files as if the content data of the files are stored locally in the storage component.
 6. The computing device of claim 4, wherein the metadata of a file include means of creation of data in the file, purpose of data in the file, time and date of creation of the file, creator or author of data of the file, location on the storage server where the content data of the file are stored, title of the content data of the file, or an inode data structure of the file, encoding format of the content data of the file.
 7. The computing device of claim 4, wherein the sample presentation of the content data of the file further includes at least one of: a reduced-size version of the content data, or a sample clip or image of the content data.
 8. A computing device having a file system that can surpass physical storage limit, comprising: a processor configured to identify one of multiple files of the computing device that has a high probability to be read by the computing device; a file system manager which, when executed by the processor, controls the files and handles file system operations to the files; a storage component configured to store metadata of the files without permanently storing content data of the files, wherein a storage server stores the content data of the files; a networking component configured to retrieve the content data of the file from the storage server after the processor identifies the file; wherein the file system manager is capable of controlling files having a total size exceeding a physical storage limit of the storage component; wherein the file system manager handles a write request to a file by a process including: determining whether the storage component stores the content data of the file on the computing device; based on determining that the storage component does not store the content data of the file on the computing device: recording, into a log data structure, a plurality of sequential changes to the content data based on the write request, and sending the log data structure to the storage server so that the server applies the plurality of sequential changes to the content data of the file in the storage server based on the log data structure.
 9. A method comprising: receiving, at a file system manager of a computing device, an instruction from a first application running at the computing device to create a file stored at the computing device; creating, by the file system manager, the file by storing metadata of the file in a local storage device of the computing device and transmitting content data of the file to a storage server, wherein the metadata includes a link to a location where the storage server stores the content data of the file; receiving, at the file system manager, an instruction to read the file from a second application running at the computing device; retrieving, by the file system manager, the content data of the file from the storage server based on the metadata including the link to the location; providing, by the file system manager, the content data to the application as if the local storage device stores the content data of the file; identifying, by the file system manager, a file having a tendency to be read by the computing device in future based on a file access pattern discovered by the file system manager, wherein the file having the tendency to be read by the computing device in future can be identified further based on file access patterns discovered by other computing devices connected to the storage server, wherein greater weight is given to the file access patterns discovered by the other computing devices associated with respective users determined to be similar to a user of the computing device; and caching the identified file in the local storage device by retrieving the content data of the identified file from the storage server.
 10. The method of claim 9, further comprising: presenting, via an output device of the computing device, the file as a file stored in the local storage device of the computing device based on the metadata of the file.
 11. The method of claim 9, wherein the first application and the second application are the same application.
 12. The method of claim 9, wherein the file system manager maintains a file system including files for the computing device having a total size larger than a storage limit of the local storage device of the computing device.
 13. The method of claim 9, wherein applications running at the computing device read files managed by the file system manager of the computing device as if the content data of the files are stored in the local storage device of the computing device.
 14. The method of claim 9, wherein the storage server stores at least a portion of the metadata of the file.
 15. The method of claim 9, wherein the storage server stores at least a portion of content data blocks of the file.
 16. The method of claim 9, wherein the file system manager stores the content data of the file at the computing device before transmitting the content data of the file to the storage server.
 17. The method of claim 1, further comprising: determining the at least one storage object that has the high possibility to be read by the computing device based at least in part on a usage profile, wherein the usage profile includes information on past usage of the plurality of storage objects on the computing device and respective indicated physical locations of the computing device in the past when the respective storage objects were accessed.
 18. The method of claim 17, further comprising: determining the at least one storage object that has the high possibility to be read by the computing device based at least in part on the usage profile and a determined current physical location of the computing device.
 19. A method comprising: storing, at a computing device, metadata of a plurality of storage objects in a file system of the computing device without permanently storing content data of the plurality of storage objects, wherein a storage server stores the content data of the plurality of storage objects, wherein a file system manager controls the plurality of storage objects and handles file system operations to the plurality of storage objects, the file system manager being capable of controlling storage objects having a total size exceeding a physical storage limit of the computing device; storing, at the computing device, the content data of at least a portion of at least one of the plurality of storage objects; identifying a storage object of the plurality of storage objects that has a high probability to be read by the computing device; retrieving content data of the storage object from the storage server after the storage object is identified; receiving a write request for a first storage object; determining whether content data of the first storage object is stored at the computing device; and based on determining that the content data of the first storage object is not stored at the computing device: recording, into a log data structure, a plurality of sequential changes to the first storage object based on the write request, and sending the log data structure to the storage server so that the storage server applies the plurality of sequential changes to the content data of the first storage object stored in the storage server based on the log data structure. 